The ground gradient is an important parameter for earthquake prediction and monitoring the security of dams or slopes. In order to get an accurate forecast, high accurate ground gradient changing parameters are required. The main devices presently used for observing ground gradient changes are horizontal pendulum ground surface tiltmeter and vertical pendulum ground surface tiltmeter, when using these two kinds of devices for measuring ground gradient changes, people often use their eyes to capture data, namely use eyes directly capturing the indicating value from the dial disc of the ground surface tiltmeter. As a result of resolution of human eyes, its reading often has some error. When a slight ground gradient change of the earth crust occurs, such reading is not easy to cause people's attention, and the sensitivity is not high. Presently electronic transducer is also used to convert the slight displacement change of the ground surface tiltmeter to electrical signal, which greatly improving the measuring accuracy and sensitivity of the ground surface tiltmeter, but this kind of transducer requires high precision, accurate processing and installation, thus the cost of the ground surface tiltmeter increases and its price will be high.